Converting Machine Inspection for Transparent Coating Alignment
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Solution Overview
Problem
Conventional systems struggle to detect transparent coatings such as varnishes with high precision in packaging containers, and there is a need for improved detection of both coatings and colors with high accuracy.
Innovation Solution
An inspection device is designed with a camera and illumination system that utilizes specific angles for capturing specular reflections from reflective coatings and diffuse reflections from colored inks, employing a first illumination module for reflective coatings and a second module for colored inks, with adjustable light intensity to optimize image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional camera system is used to detect printed reference marks, then color alignment can be detected, but transparent coatings such as varnishes cannot be detected
Solution Approach 1:
The patent applies optical interference effects by controlling the angle of incident light to create visible interference patterns on transparent coatings. When light strikes the coating at a specific angle (first angle different from second angle), constructive and destructive interference occurs, making the transparent coating visible to the camera sensor without altering the coating itself
Solution Approach 2:
The patent changes the optical parameters by using illumination units positioned at specific angles relative to the camera. The first angle of incident light and second angle of reflected light are carefully controlled to maximize the visibility of transparent coatings through interference effects, transforming an invisible parameter (transparent coating) into a visible one
2Measurement precision
If illumination intensity is increased to improve coating detection, then detection precision improves, but risk of specular reflection interfering with color detection increases
Solution Approach 1:
The patent divides the illumination system into multiple separate illumination units, each positioned at different angles. This segmentation allows independent control of illumination angles, enabling the system to optimize for both coating detection (through interference patterns) and color detection (by minimizing specular reflection into the camera) simultaneously
Solution Approach 2:
Different regions of the inspection system use different illumination strategies. The illumination units are positioned with specific angular relationships to the camera, creating localized optimal conditions for detecting transparent coatings through interference while preventing harmful specular reflections from reaching the camera sensor
3Device complexity
If a single illumination system is used for both coating and color detection, then device complexity is reduced, but detection precision for both coatings and colors cannot be optimized
Solution Approach 1:
The illumination units serve multiple functions simultaneously: they provide the angled incident light necessary for creating interference patterns on transparent coatings, while also illuminating the printed reference marks for color detection. This multi-functionality allows a single illumination system to optimize both coating and color detection precision without requiring separate independent systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves precise detection of both reflective coatings and colored inks by optimizing illumination angles and intensity, ensuring accurate alignment and positioning of printed motifs on packaging containers.
Implementation Method 1
the first and second angles are selected such that incident light rays from the illumination unit are directed to the reference mark and specular reflected light rays from the reference mark are captured by the camera
Implementation Method 2
The present invention is based on a realization that reflective coatings can be detected by creating a mirror effect from the coatings which is received into the camera
Data Source
AI summary
The invention relates to an inspection device (42) for checking the position of at least one coating on a blank (1) transported through a converting machine (10). The inspection device comprising a camera (49) configured to capture an image of a portion of the blank provided with a reference mark (30) comprising at least one coating,An optical axis (A) of the camera is arranged at first angle (φ) in relation to a vertical axis (V) defined by a normal vector (N) of a surface of the blank (1). An illumination system (50) is configured to emit incident light rays towards a measuring point (Pm) on the blank 1. The incident light rays from the illumination system are directed to the reference mark and specular reflected light rays from the reference mark are captured by the camera.